Center-finder



G. w. HARRIS. CENTER FINDER.

APPLICATION FILED MAYIS. 1920.

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UNITED sTATEs PATENT OFFICE.

GEORGE W. HARRIS, OF MODESTO, CALIFORNIA, ASSIGNOR OF ONE-HALF T0 AUGUST C. FINGERLE, OF MODESTO, CALIFORNIA. I

CENTER-FINDER.

Specification of Letters Patent.

Patented Mar. v1, i921.

To all whom it may concern:

Be it known that I, GEORGE W. HARRIS, a citizen of the United States, residing at Modesto, in the county of Stanislaus and State of California, have invented certain new and useful Improvements in Center- Finders, of which the following is a specification.

This invention relates to geometrical instruments, and more especially to point markers; and the object of the same is to produce an improved center finder.

The object is carriedout by employing a set of caliper arms pivoted to a nut through which passes a screw, a plate swiveled on the screw, and links connecting the plate with the arms; and employing also a center' punch slidably mounted through the screw so that it may be manually projected to mark the center desired.

Details of constructionvare set forth in the following specification and claims, and reference is made to the drawings where- 1n:-

Figure 1 is a. plan view of this device complete,

Fig. 2 is a vertical sectional view therethrough,

Fig. 3 is a sectional detail on the line 3 3 of Fig. 2, and

Fig. 4 is a perspective detail of the point of one of the caliper arms.

Through a long nut 1 is threaded a tubular screw 2 having a hand wheel 3 fast to its upper end above the nut and a plate 4: swiveled on its lower end as shown. The plate preferably has four arms indicated at 5 in Fig. 3, each notched at its outer end as at 6, and by preference this plate is made in two parts meeting on a transverse line which intersects the bearing for the screw 2, the parts being held together by rivets or screws as indicated at 7. Slidably mounted through the bore of the screw is the center punch 8 Whose upper end has a knob 9, and a light spring 10 interposed between the knob and the hand wheel 3 holds the punch normally raised. The lower end of the punch is shaped and tempered so that a slight indentation in the work may be made to indicate the center when it is found by a blow on the knob 9.

The nut 1 in the present instance has four radial arms 15, each notched at its outer end as indicated at 16, and within each notch is pivoted at 17 the upper end of a caliper arm 18 whose body by preference is of the shape shown in Fig. 2. F ourf links 11 are pivoted at 12 at their upper ends to said arms and at 13 at their lower ends within the notches 6 of the plate, and these links may have the configuration shown in Fig. I wish to state 'at this point that, Whereas I have shown four arms and links and vfour notches each in the nut and plate, itis quite obvious that a larger number could be employed ora smaller number, but I prefer not tohave less than three. The active or lower ends of the caliper arms 15 have points 19 adjacent their extremities 2O which latter constitute shoulders.

In the use of a device of this character, let us assume that a center is to be found on a round-plate. The nut and the upper portions of the arms 18 `are held in one hand, and the hand wheel 3 turned in a proper direction to spread the lower ends of the arms until their points 19 are sutliciently far apart to pass over the edge of said plate. The hand wheel is then turned in the reverse direction until the shoulders 20 pass over the upper corner of the plate and the pins or points 19 rest against its edge; and now a sharp blow on the knob 9 impels the punch 8 downward and its tip makes a slight indentation in the upper face of the plate and exactly at the center thereof, the spring 10 immediately retracting the punch to about the position shown. If there is an even number of arms 18, it is obvious that the point can be utilized for bisecting a straight line or finding the intermediate position between two given points; but when used strictly as a center finder, three arms will be sufficient.

The foregoing description and the drawings have reference to what may be considered the preferred, or approved form of my invention. It is to be understood that I may make such changes in construction and arrangement and combination of parts, materials, dimensions, et cetera, as may prove expedient and fall within the scope of the appended claims.

Having thus fully described my invention. what I claim as new and desire to secure by Letters Patent is 1. In a center finder, the combination with a nut, a tubular screw passing therethrough, a plate swiveled on the screw, and a punch longitudinally movable through the screw; oi a plurality of caliper arms pivoted at their upper ends to said nut, and links pivoted at their lower ends to said plate and at their upper ends to said arms respectively.

2. In a center finder, the combination with annut, a tubular screw passing therethrough, a plate swiveled on the screw, and a punch longitudinally movable through the screw; of a hand wheel xed on the screw above said nut, a knob atthe upper end of said punch, an expansivespring between the knob and hand wheel, a plurality of caliper arms pivoted to said nut, and means pivotally connecting said plate and arms for separating the latter `and retracting the same when the nut is moved upon the screw.

3. In ay center nder, the combination with a nut, a tubular screw passing therethrough, a plate swiveled onjthe screw, and a punch longitudinally movable through the screw;

of a hand wheel on the screw atbove said nu't, a'knob at the upper end of said punch, anexpansive spring between the knob and hand wheel, a plurality of caliper arms pivoted at their upper ends to'said nut and with their lower ends adapted to pass under said screw.l and links pivoted at their lower ends to said plate and at their upper ends to the arms respectively, for thepurpose set forth.

4. In a center finder, the combination with a long nut having four radial arms notched at their outer ends, a hand wheel above said nut, a screw fast within the hand wheel and passing through the nut, and a plate swiveled on the lower end of the screw and having four radial arms notched at their outer ends; of a punch slidable through the bore of said screw and having a head at its upper end, four caliper arms plvoted at their upper ends inthe notches of the arms on the nut and having points atl their lower ends, and four links respectively pivot-ed in the notches in said plate at their lower ends and to said caliper arms at their upper ends, for the purpose Set forth. f5. In a center finder, the combination with a nut, a tubular screw adjustable therethrough, a punch slidably mounted through the bore of the screw, and a plate swiveled on the lower end of the screw; of four links pivotally connected with said plate and rising therefrom, our'pcaliper arms pivoted to said nut and depending therefrom, their bodies being pivotedto the upperends ot' said links respectively, and on each army a pendant'poin't adjacent its extremity leaving a shoulder at the latter, for the purpose set forth. n 1 v In testimony whereof I atlix my signature in presence of two witnesses.

i GEORGE W. HARRIS.

Witnesses:

E. H. RxoN, A. E. WAKEFIELD. 

